We have a tap room and a main room, and to avoid jams (and the spillage of precious, precious beer), we have a one-way system through the tap room.

The signs for this are literally half a metre high (this is in a church hall, so a main room probably about the size of a basketball court, with a three metre ceiling) and say simply "TAP ROOM" and "NO ENTRY". (For the avoidance of doubt, everyone who goes to a beer festival knows what a tap room is; even the worst drunkenlogic can figure out that if there's no beer in HERE, there must be beer in THERE)

And people still ask where the tap room is, and walk in through the out door.

I will be advocating for making these signs bigger this year. And possibly audible. Probably explosives. And fireworks. And dancing girls.